This invention relates to water separation cells for removing the reaction water from the electrolyte of fuel cells and fuel cell batteries in general and more particularly to an improved cell of the type having a liquid chamber bounded on at least one side by a porous diaphragm and a gas chamber bounded by the diaphragm and a condensation surface adapted for cooling.
A method for separating the reaction water from the electrolyte of fuel cells or fuel cell batteries in which electrolyte conducted in a closed circuit is led through a water separation cell and is there brought into contact with one side of a diaphragm, and the water vapor is transported through the diaphragm into a gas chamber adjacent to the former is already known. The hydrostatic pressure of the electrolyte in the porous diaphragm is compensated either by the pressure of a gas present in the gas chamber or by the capillary depression pressure prevailing in the diaphragm, and the water vapor is condensed at a cooled condensation surface which forms a boundary surface of the gas chamber opposite the diaphragm. Apparatus for implementing the method comprises a water separation cell which is arranged in an electrolyte loop outside the fuel cell battery and contains a liquid chamber through which the electrolytic liquid flows. The liquid chamber is bounded, at least in part, by the diaphragm, which forms the one wall of the gas chamber which is bounded on the other side by the condensation surface (German Pat. No. 1,671,879 or British patent Specification No. 1,208,671 ).
The separation of the reaction water according to this diffusion-condensation principle has proven itself in practical use. The water separation cell or the gas chamber bounded by a nonporous condensation surface is in general connected to a lock for the continuous automatic removal of the condensed water, i.e., the condensed reaction water. A porous disk is arranged in this lock through which the separated reaction water is removed (German Pat. No. 1,273,644 or U.S. Pat. No. 3,479,224).
An auxiliary gas under pressure, usually hydrogen which is taken from the fuel cell or the fuel cell battery is used for transporting the condensate from the gas chamber of the water separation cell to the lock. This auxiliary gas passes into the environment following the lock, which results in a large gas consumption. If hydrogen is used as the auxiliary gas, measures must be also taken to prevent the development of explosive hydrogen-air mixtures.